(a) Field of the Invention
The present invention relates to an automatic packaging system capable of performing, in an integrated process, fabrication, filling and sealing of rectangular-prism-shaped (or rectangular parallelepiped) packaging containers for packaging a liquid, such as juice, liquor, milk, etc.
(b) Description of the Prior Art
An automatic packaging system has recently been developed which fabricates bottomed, hollow rectangular-prism-shaped containers from laminated paper with thermoplastic films, such as polyethylene, on both sides thereof, fills the containers with a filling material, and then seals the openings of the containers to complete packaged products. In the prior art automatic packaging system, however, a mechanism for forming a tubular structure from a laminated sheet coated with polyethylene or other heat-sealing material, cutting the tubular structure into containers of a suitable size, and delivering the containers to a rectangular container end processing mechanism may damage the container material due to its imperfect function. Also, a forming unit of the container end processing mechanism may produce defective products, or a conveyor mechanism for formed containers may be complicated in structure. In heat-sealing the openings of the rectangular containers after filling the containers with contents, moreover, excessive air may remain in the top inside spaces of the containers to bulge the trunk portions thereof, complicating the removal of the containers from the conveyor mechanism and lowering the commercial value of the products. According to the conventional system, furthermore, the rectangular containers may be deformed when triangular lugs produced by heat-sealing the openings of the containers are folded and sealed on the top faces of the containers. If the containers are filled with a heated material, moreover, residual air in the containers will be heated and expanded by the heat of the filling material to bulge the top portions of the sealed containers. Accordingly, the containers will not be able to be smoothly transferred from the conveyor mechanism to another conveyor mechanism.